Submarine mine



April 3, 1946. w. R. MALTB Y V I 2,398,794

' SUBMARINE MINE Fil ed July 30, 1941 4 Sheets-Sheet l INYENTOR W. R.MALTBY April 23, 1946. w R MAL-[BY 2,398,794

' SUBMARINE MINE Filed July so, 1941 4 Sheets-Sheet 2 INVENTOR W. R.MALTBY April 23, 1946. w. R. MALTBY SUBMARINE MINE Filed July 30, 1941 4Sheets-Sheet 5 INVENTOR W R. MALTBY vl! lllrl Iii April 23, 1946. w R MY 2,398,794

SUBMARINE MINE Fil ed Juiy so, 1941 4 Sheets-Sheet 4 INVENTOR w. R.MALTBY I ATTO EY Patented Apr. 23, 1946 I want- SUBMARINE MINE Wilson B.Maltby, Washington, D. 0.

Application July 30, 1941, Serial No. 404,608

(Granted under the act of March 3, 1883, as amended April 30, 1928; 3700. G. 757) 20 Claims.

This invention relates to a submarine mine of the induction or gradienttype in which the mine is caused to be fired by the passage of a steelvessel or any vessel having a ponderance of magnetic material within aneffective area adjacent the mine whereby the destructive effect of themine upon the vessel will be assured. More specifically the inventionprovides a new and improved submarine mine adapted to be launched froman aircraft in flight in which means are provided for causing the mineto come to rest on the bed of a body of water with the mine in avertical position.

In devices of this class heretofore devised, it is the general practiceto allow the mine to come to rest in a random position determined onlyby such fortuitous circumstances as may be present incident to thelaunching of the mine. It is the usual pratice in devices of thischaracter to suspend the mine firing control unit on gimbals, wheneverpracticable, in order that the firing control mechanism may be placed ina predetermined position regardless of the position of rest that themine has assumed. In the case of mines employing induction orgradiometer type coils for the control of the firing mechanism, thelength of the coil employed precludes the effective use of gimbals forsupporting the coil structure and such mines have been subjectheretofore to the disadvantages which result from the placement of theaxis of the search coils employed in varying degrees of tilt including atilt to the horizontal position.

One of the objects of the present invention is the provision of new andimproved means for directing a submarine mine along a predetermined pathof flight when launched from an aircraft, for automatically deceleratingthe rate of travel of the submarine mine during passage of the minethrough the body of water within which the mine has been launched,andfor causing the mine to come to rest in an upright position on thebed of the body. of water.

Another of the objects resides in the provision of new and improvedmeans for rigidly supporting the mine in a predetermined position as themine comes to rest on the bed of a body of water within which the minehas been launched.

Another of the objects is the provision of means effective as the minestrikes the bed of the body of water within which it ha been launchedfor engaging the bed at different points whereby the mine is firmlybraced in a vertical position regardless oi the contour of the bed withwhich the mine is engaged.

Other objects and advantages will be apparent from the followingdetailed description, taken in connection with the accompanyingdrawings, of which:

Fig. 1 illustrates the invention according to a preferred embodimentthereof;

Fig. 2 is a View in section, somewhat enlarged and partly broken away,of the device of Fig. 1;

Fig. 3 is a view in elevation of the device of Fig. 2 with the finsthereof in open position;

Fig. 4 is a view partly in section and somewhat enlarged of the finoperating and latching mechanism;

' Fig. dis a view taken substantially along the line 5--5 of Fig. 4 withthe fin in an extended position;

Fig. 6 is a view partly in section and partly broken away illustratingthe fin releasing mechanism; 4

Fig. 7 is an end view of the device of Fig. 6; and

Fig. 8 illustrates diagrammatically an electrical circuit arrangementsuitable for use with the presentinvention.

Referring first to Fig. 1 of the drawings there is shown thereon asubmarine mine indicated generally by the numeral l adapted to bereleased-in any well known manner from an aircraft in flight such, forexample, as illustrated at 2, the path of travel of the mine beingindicated generally by the dashed line 3. The mine is provided with aplurality ofrotatable members or fins 4 pivotally mounted as at 5 butnormally restrained from movement until released by a hydrostatresponsive to the pressure of the water within which the mine islaunched whereby the members 4 are first employed as stabilizin planesor fins to guide the mine along a predetermined line of flight afterbeing released from the aircraft and are subsequently employed todecelerate the mine during the descent'th'ereof through the Waterwhereby the mine will strike the bed of the body of water at a somewhatreduced rate of travel. At the instant of impact with the bed, themembers are quickly brought into engagement with the bed thereby tomaintain the mine securely braced in an upright position regardless ofthe contour of'the bed of the body of water with which the mine isengaged.

The mine is provided preferably with a piercing member 6 adapted topenetrate the bed of the body of water and prevent substantial movementof the mine from any cause such, for example, as the action of tidalcurrents or a shifting condition of the bed. As illustrated'on Fig. 1,

the mine is adapted to be braced in a vertical position on a relativelylevel bed of a body of water, on an inclined portion of the bed or upona rock or reef such as illustrated at 1, 8, and 9, respectively.

On Figs. 2 and 3 is shown a submarine mine according to a preferredembodiment of the invention comprisingacasing l l towhichis afiixed thepiercing member 64 The casing-isprovided' with a tapered portion l2having .a cylindrical member l3 secured thereto as by the bolts I4,

suitable gasket [5 being provided preferably to insure a watertightconnection between the cas ing and the tapered portion I2. member I3 asbythe bolts I6 is the member IT,

a suitable gasket I8 being preferably inserted-- therebetween to preventthe seepage of zwatei" within the mine. The member I1 is provided with abearing support or strap l9,-iFig-.' 6;-secured:

thereto in any suitable manner as by the bolts 2 I, and having abearing;22 therein in alinement with the t bearing- 23; whereby the"hydrostat plunger-24 is slidably-supported. Aflexibledia phragm 25 issecured in sealed relation to-the position illustrated -unti'l the:minehas attained a;

predetermined depth of submersion withingthe water,- at:w-hich;- timethe pressure of the water against the flexible diaphragm 25 'causesith'eextending members 3| of the latch 29 to be With-- drawn from lookingengagement with the'finretaining hasps 33;pivotal-ly;secured to the finsas by the pins 34.

Anarming wire .35 passes throughan aperture 36 within the plunger rod 24and the bearing sup-v ports ,3! extending ;from the-memberwlv'l wherebythehydrostat is prevented from movement until, after the arming wire isWithdrawn. ThearI-ning wire extends through an aperture .38 --withi nthe member; I 1 and issecured'at the other end thereof;;to the aireraftWherebYJthe arming wireisw-ithdrawn fromthe mine-as the'mine,fallsawayrii om,

the aircraft.- 1

mped: to th mi i ca in I l as by the bolt 39 is; an adjustable support140 comprising ;fou r bearing, pieces 4 I and a plurality g-ofbrackets-(42 adaptedto receive a bearinggpin: 43 held in posirotatablemember '45 having; a ratchet device 46 grooved arcuate portion 50 of theratchet 46 and is guided by a suitable grooved pulley pivoted on thebearing shaft 51 supported by the bearing pieces 4|. A pair of pawls 58and 59, Figs. 4 and 5, are pivotally supported on the shaft 51 and urgedby the springs BI and 62 respectively encircling the pin 53 toward theratchet 46 until arrested by the @portion;-;-64- there0f whereby thepawls are preventedjfrom engaging gthe arcuate portion 65 of the ratchetand are efiective to engage any of the teeth 66 of the ratchet as thefin '45 is moved to an extended or open position. Pawl 59, it willbenoted, is preferably somewhat longer than the pawl- 58 by an amountsubstantially one-half theidistance between the tips of adjacent teeth66 of the ratchet, thereby providing an arrangementimwhich the angulardistance between successive locking positions of the fin is one-half theangular .,distance1b'etween successive teeth of the ratchet. Thus,larger teeth on the ratchet may be employed in: which the strength ofthe ratchet mechanism -is;' substantially l increased: This 'arrangementis clearly ;shown- -on-Fig. 5 by reason of-the fin Ali-having beenrotated, for purposes of illustration,- through. an angular distance of-90 degrees from-the-position shown: on Fig. 4.

The support55:is:of-a shape adapted to engage.

and additionally support the fin 45 during the fiightof the mine in-theair and the passage of themine throughthe :water until-the vhydrostatt25 has released' the fins which are moved bythe: springs 52 out of engaement with the supportsv 55. By pivotally supporting the fins" at. thepins 43 and additionallysupporting the finsyby means of; the brackets 55in the manner herein disclosed;

the 'fins are rigidly held vin-a predeterminedw 1305i? tion inalinementwith the axis of the mine wherebythe mine followsapredetermined line of flight and maythus be plantedlin a predetermined"location with a high degree .of accuracy.

Attached ;to-;the adjustable support- 148 insubstantial;alinement'with'therfins 45'are thev or wedge shaped members61 whereby, during the descent \ofithei-mine withinr'the water; afterthe fins r-have'beenire'leasediby the hydrostat, the

members 67 deflect the pressure of the water from the finssufiiciently:to'permit the Lfins to 'bepartially:,extend'ed {by the. springs-"52 mthe .manner secured thereto in any;suitablemanner such,;for 7 example,as by; welding .jOI brazing ,:the parts together is pivotally mounted.on the pin} 43 Where? by the member 45 may be rotated to differentpositions as will more clearly appear as thedescri-p tion, -procee,ds.-The member :45 is generally. U-v

shaped, Fig.:7, and provided-g; with {reinforcing strips securedthereto; such; foniexample as the,

channel fshapedpieces '41,. illustrated:

A: flexiblev ,;cable. 148; Fig. .4, 4 of steel, oresimilar materialsuitable for @the purpose, :is: secured; at-

one, end thereof to the ratchet .41'3,as.b'y'theplate- 49' and bolts 5l, and. at the. other-Lend vthereof ;to a retractile spring; 52;:asgbyvthe clamp; 53 and bolt 54.- The'o'ther end of the retractilespring "is attached-to a supp0rt 55 securedtovthe casing-ofthe minewherebythe ,retractilespring. is' maine.

tained in tension sufficient to ;cause -the ;fin- 45 to. be actuated tothe, open position-shown; on Eig;-;3.- The; cable- 48 passes 1 alonga-soom-pl ernentary;

shown=onFig;;l.- The rate of descent of the mine is thus diminisheddmtilthe minelstrikes the bed of the ,body ofwatenrat; FWhiCh: time theinertia. of the partially extendedxfihsiis employedto assist the springs52 in quickly lowering the fins into engagement Withthe bed of thebody'of-water before the -mine-has tilted'by an appreciabl'etamount'fr-ornvthevert-ical position; Each of the'fins is restrainedfrom-reversemovement by the pawl 58 or :59; as thecase' may-"be, wherebyithe mineispositively gset =to a'predetermined' :verticat position.q Theadjustable-support 148 may; if desired,

' m t: different positions with respectito the mine casing l l2whereby-the position of thefins 45 may be varied at will in accordancewith' the degree ofshardness of thebed-ofi thegb'odyof waterwithin-which the mine'is; tube-planted. A p111- rality of holes60*are'provided-in each ofthe ifins 45 wherebythe-ha-sp 1maybe pivotallysecured thereto byjthe pin: :34 at-'different: positions in accordancewiththe adj-us-tedpositionv'of the support;40. .If foreXamplerthe-m-in'eisto belaunched in a 'bOdYTDf water having arrelatively. soft :bed,

it, maybe :desirable, in: viewro-f, the a greater pene trationgoftheminewithin the bed before coming.

to'reshto arrangethe support '40 somewhat-nearer the tail of the minewhereby the.vfins;45 :maynbe.

employed to greater advantage in supporting and maintaining the mine ina vertical position.

. The operation of the mine firing mechanism will now be described.Assume, by way of example, that the mine has been launched and isresting on the bed of a body of waterin a vertical position with thefins thereof locked i supporting engagement with the bed and thatsufficient time has elapsed after the mine has been launched for thesoluble washer 68 to dissolve or soften sufficiently to allow thehydrostat 69 to be operated by the pressure of the water. When thisoccurs, the detonator H is inserted into the booster charge 12 withinthe casing 13 and the electrical contact members M are brought intoengagement with each other by movement of the collar 75 preferably ofinsulating material suitable for the purpose such, for example, asBakelite, rubber or the like, afiixed to the hydrostat.

A battery BA is provided within the compartment 16, Fig. 6, andinsulated therefrom by suitable yieldable material such, for example, assponge rubber or the like in the manner illustrated and in circuit withthe armature spring I! of relay F, the circuit being continued by way ofthe cable duct '58 to the hydrostat contacts i5 and thence to thedetonator H. A search coil SC preferably having a magnetic core 80therein is operatively connected to the winding of relay F as by theconductors l9 and adapted to operate the relay in response to a changingfield detected by the search coil within the effective destructive areaabove the mine. Thus, the electromotive force generated by the searchcoil, as a steel vessel passes within the effective area of the mine, isof sufiicient strength to operate the relay F and cause the detonator tooperate and fire the booster charge 72 thereby causing the main charge19 to explode the mine.

Whereas the preferred illustrative embodiment of the invention has beendescribed with particular reference to a submarine mine in which aninduction coil is employed to control the mine firing mechanism, it willbe understood that the present invention may be applied to mines inwhich the presence of a steel vessel is detected by search coils of thegradient type wherein the diiferential voltages induced within thesearch coils by the moving vessel is employed to fire the mine. Theinvention may also be employed with mines in which the detectingmechanism is preferably directionally disposed such, for example, asmines employing acoustically controlled detecting mechanisms.

Briefly stated in summary, the present invention provides means forguiding a submarine mine both through the air and in the water along apredetermined line of flight and causing the mine to come to rest and bebraced in a vertical position on the bed ef the body of water withinwhich the mine has been launched. Thus, by reason of the predeterminedposition of rest of the mine, the area detected by the detectingmechanism is reduced and a more effective use is made of the mine forthe purpose of disabling or destroying a vessel.

While there is shown and described herein a certain preferred embodimentof the invention, many other and varied forms and uses will presentthemselves to those versed in the art without departing from theinvention, and the invention, therefore, is not limited either instructure or in use except as indicated by the terms and scopeof theappended claims.

- The invention herein described and claimed may be manufacturedfandused by or for the Government of the United States of America forgovernmental purposes Without the payment of any royalties thereon ortherefor.

What is claimed as new and desired to be secured by Letters Patent ofthe United States is: 1. In a mine ofthe character disclosed adapted tobe laid on the bed of a body of water, a mine casing having a pluralityof fins pivotally secured thereto and settable to an initial positionand to a final position in which the fins are adapted to support themine in a predetermined position on said bed, means for locking saidfins in said initial position, means eifective during the descent of themine through the water for causing the fins to be released from saidlocking means, and means for actuating the fins to said final positionas the mine strikes the bed of the body of water within which the minehas been launched.

2. In a mine of the character disclosed adapted to be laid on the bed ofa body of water, amine casing having a plurality of fins pivotallysecured thereto and settable to an initial position and to a finalposition in which the fins are adapted to support the mine in apredetermined position on said bed, means for locking said fins in saidinitial position, means effective during the descent of the mine throughthe water for causing the fins to be. released from said locking means,means for actuating the fin to said final position as the mine strikesthe bed of the body of Waterwithin which the mine has been launched, andmeans for retaining the fins in said final position.

3. In a mine of the character disclosed adapted to be laid on the bed ofa body of water, a plurality of rigid members pivotally secured to saidmine adapted to brace the mine in an up-' right position as the minecomes to rest on said bed, means'for maintaining the members in a closedposition as the mine is launched, means including a device responsive tothe pressure of the water within which the mine is immersed forreleasing said rigid membersand means eiTective as the members arereleased for actuating the members to an open bracing position.

1 4. In amine. of the character disclosed adapted to be laid on the bedof a body of water, a pluralityof rigid members pivotally secured tosaid mine adapted to brace the mine in an upright position as the mineengages said bed, means for maintaining the members in a closedpositionas the mine is launched, means including a device responsive tothe pressure of the water within which the mine is immersed forreleasing said rigid members, means efiective as the members arereleased for actuating the members to an open bracing position, andmeans including a ratchet mechanism for locking said rigid memb'rsin'said open bracing position.

, 5. v In a submarine mine adapted to be launched froman aircraft inflight, the combination of a plurality of fins pivotally secured to saidmine, fin actuating means for pivotally moving the fins from apredetermined initial position to a final position in which'the fins areadapted to support the mine in a predetermined launched position, meansfor retaining said fins in said predetermined initial position, anarming wire secured to said aircraft and adapted to unlock said finretaining means as the mine falls away from the aircraft in flight, andmeans for rendering said fin retaining means inefiective to maintain thefins insaid predetermined initial position during the travel of themin'eathrouglrthe b'odybf water within-which the mine {is launched 6.Ina submarine-mine adapted to be laun'che dplurality of fins pivotall ysecuredLtO saidimine; fin actuating means for pivotally movi-ngthefinsfrom a predetermined ini tial position' toa finalposition in which thefins' are' adapted to support the mine in a predetrmi-ned -lafihch'edposition," means for retaining saida fin'sin saicl prede'ter minedinitial position; an arming wire seeured to said aircraft and adapted-to' unlock said -fin-v-re taining means as "the-mine falls awayfrom'=the-' aircraft *in flight, means for rendering said fiiiretainingmeans ineffective-to maintain'the fins in said predeterminedinitial position during the travel of the mine through' the body ofwater within which the mine has -'been"launch'ed,- and means secured tosaidminefor causingthe fins to be'actuated to a predetermined setting'''during the descent 'of -the mine-through said body of water." 7

'7. In a'mineof the character-disclosed adapted to be launched'from anaircraft infiig'ht,- the com-'- bination of a plurality of rigid memberspivotally and releasably secured to said mine for directing the minealong a predetermined lineof 'fiight," means effective during thedescentof the-mine through the water for releasing said rigid mem b'ers,"andmeans efiective as the-mine strikes the bed of the body of water forcausing said'rigid members to be actuated into engagement with saidbedvariably, in accordance .With the contour of said bed therebyto'support the mine'inavertical position.

8. In a mine of the"characterdisclosed adapted to be launched from anaircraft in"flight,"the combination of a pluralityrof rigid memberspiv;otallyand releasably secured "to saidrniriefor di recting' the minealong 'a predetermined line of flight, means effective'duringqthedescen'tof 'th'e mine "throughith'e water for releasing "said frigidmembers; means effective as the 'mine strikes" the bed "of the body"of'wate'r for causing said" rigid members to "be iactuatedvariablyto'positions in engagement with said bed infa'c'cordan'ce with the contour:of the bed "thereby "td support 'Isai'd' mine in a vertical position;and .nieansfor looking said members-in said actuatedpositions";

9; Ina submarine mine adaptdto be launched froman aircraft 'ififiight,"mean's' efiective'as the mine comes torest on'the bedof"a.body'"oi"water within whichthe' "mine has"beemlaunched'iforenga'gingsaid bed 'and' supporting the mine ma redetermined-- position?means for-locking ".sa'id minesupporting "means in *an initial position:an armin wire secured to said" aircraft for removing a restraintsaid*lockingfmeans-"as the "mine falls away fromsaidaircraft;meanscontrolled by thepressure of=the*water for rel'easing saidddck ingmeans, mean's for-" actuatihg "said*minesup-"- porting means to aposition"in whichthe rate'of travel of the mine-through the waterisreducedand foraddition ally'actuatingthe mine support ing means as'themine strikes said-bediandmeans forlatching said bracing means'-iriengagement with the bed-bf the body of water inaccorjdance 7with'the contour of said bed i 10. -In' a mine of the characterdisclosed adapted to be launched from an aircraft infiightfthecombination of'a pluralityof fins"pivotallyse cured to said mine,meansfdractuating'said-fins to' different-'-positions,--a "ratchetmembersecured to ea'ch' of saidfin's having a pluialityof ratcht' teeth'thereon; a ai1- ori aw1s adapt d toenea' e the teethi ii of I each:ratchet --member alternately as thevfin' is a'ctuated to successivepositions for lockin'gieach'of said fins in different positionsinaccordance wit'h the contour 0f the bed of the' bodylof water with whichthe fins are engaged;

11. In a mine of the character disclosed adapted tobe launched from anaircraft infiightthe combination "of a plurality of finspivota'llysecured to said mine, means for actuating said finstozdifierent positions; a ratch et member securedto each of'said finshaving a plurality of ratchet teeth thereon, a pair of pawls adapted toengage the te'eth ofeach ratchet member alternately as the fin isactuated to successive positions for lockingeach of said fins indifferent positions in-accordance with the contour of the bed of thebody -of water with which the fins are engaged,- an'dmeansfoir urgingsaid pawls against said ra'tchet member. a

12. In a submarine mine adapted to be launched from an aircraft infiight, a plurality'of fin'members for controlling the flight of saidmine through the air, a plurality of pivot supports'for-said fins, meansfor moving said fins into engagement with the bed or the body or waterwithin which the mine has been planted thereby to support the mine in apredetermined position, and means for adjusting the position of saidpivot supports in'acoordance with the predetermined degree-ofpenetration of said bed by the mine;

13; In a submarine mine adapted to be released from an aircraft inflight, a plurality of fin members for controlling the flight of thereleased mine, means for pivotally supporting said fin members, meansfor locking said members in an initial position, means controlled by thepressure of the Water within which the mine is submerged forsimultaneously releasing each of the fin members from said lockingmeans, and means adapted to actuate said fin members to an outwardly eX-tending open position in which the fin members are adapted to deceleratethe descent of the mine within the water as the members are releasedbysaid releasing means. 1

14; In-a submarine mine adapted to be'launched from an aircraft inflight, the combination of a mine comprising a casing having aplurality'of movable members pivotally secured thereto and settable toan initial guiding position andcto'a final" bracing 1 position, meansfor holding the members in said initial position, a ratchet individual"to each of said members and secured thereto; aplurality of pawls adaptedtoengage the teeth" of each ratchet respectively and to retain themembers in said bracing" position,

means for releasing said holding means during the descent of the mineWithin the body of Water, and "means including a flexible member inoperative connection with each of said ratchets re-' spectively foractuating said members to said final in flight and having a plurality'of movable fins for "guiding the mine along a predetermined line offlight, a mine casing, means connected 'to'the casing forpivotally'supporting said fins. means for preventing movement of thefins from'an initial position until the" mine has been submerged to apredetermined depth within a body of'water, means including a springdevice for actuatingeachof said-fins toanoutwardlyextendingppen'pos'ition in which thefins are adapted todecelerate the descent of the mine within the water, means secured tosaid casing and adapted to be enclosed by the fins while in said initialposition for additionally supporting the fins, and means for connectingsaid spring device to the last named fin supporting means.

16. In a submarine mine of the character disclosed comprising aplurality of rotatable fins adapted to be actuated to a position inwhich the fins are adapted to support the mine in a predeterminedlaunched position, the combination of ratchet mechanism rotatable witheach of said fins, means for actuating said fins, a plurality of pawldevices for engaging the teeth of said ratchet mechanism variably inaccordance with the angular position of said fins, a pivot support forsaid pawl devices, means adapted to urge the pawls into engagement withsaid ratchet mechanism, and means for preventing the engagement of saidratchet mechanism by said pawls until the fins have been rotated by saidactuating means through a predetermined degree of rotation.

17. In a submarine mine of the character disclosed, the combination of amine casing having a plurality of fin members pivotally secured theretoand locked in an initial position, means including a device responsiveto the pressure of the body of water within which the mine has beenlaunched for releasing said fin members for rotation, means foractuating said fin members to a final setting in which the mine isbraced in a predetermined position as the mine comes ot rest on the bedof said body of water, a water hydrostat h'aving contact means adaptedto be closed as the hydrostat operates in response to a predetermineddegree of pressure of the water within which the mine is submerged,means including a relay for detecting the presence of a vessel within aneffective destructive area, detonating means, and means including afiring circuit adapted to be closed jointly by said contact means andsaid relay for causing the detonating means to explode the mine inresponse to the operation of said sensing mechanism.

18. A submarine mine of the character disclosed adapted to be laid onthe bed of a body of water, a casing for said mine having a plurality ofbracing members pivotally secured thereto and settable to an initialposition and to a final position in which said bracing members areadapted to brace the mine in a predetermined position on said bed, meansfor releasably locking said bracing members in said initial position, ahydrostat device having means for causing the bracing members to bereleased from said looking means as the hydrostat device operates, meansadapted to actuate the bracing members to said final position, aplurality of stop members secured to said casing within the path oftravel of said bracing members for arresting the bracing members in saidfinal position, and a plurality of ratchet devices respectivelyassociated with each of said bracing members for locking the bracingmembers in said final position.

19. A submarine mine of the character disclosed adapted to be launchedWithin a body of water from an aircraft in fiight, a plurality of finspivotally secured to said mine, normally locked means for releasablyretaining said fins in a predetermined initial position, an arming wiresecured to the aircraft and adapted to unlock said fin retaining meansas the mine falls away from the aircraft, means responsive to thepressure of the water within which the mine is launched for renderingsaid fin retaining means inefiective to maintain the fins in saidpredetermined initial position, and means secured to said mine forcausing the fins to be actuated variably to different positions in whichthe fins are adapted to support the mine in a predetermined position onthe bed of said body of water in accordance with the rate of travel ofthe mine through said body of water.

20. In a mine of the character disclosed adapted to be launched from anaircraft in flight, the combination of a plurality of rigid memberspivotally secured to said mine for directing the mine along apredetermined line of flight, means for releasably locking said rigidmembers in an initial position, means effective during the descent ofthe mine through the water for causing the rigid members to be releasedfrom said locking means, and means for yieldably urging said rigidmembers outwardly from the mine to different an gular positions inaccordance with the rate of travel of the mine through the water therebyto vary the effective brakin area of the members until a uniform rate oftravel of the mine is reached.

WILSON R. MALTBY.

